Anomalous Lattice Parameter of Magnetic Semiconductor Alloys

TL;DR

This paper introduces a new formula linking magnetic moment and lattice parameters in magnetic semiconductor alloys, explaining anomalous behaviors and aiding future research.

Contribution

It presents a simple, predictive formula for lattice parameters in magnetic semiconductors based on first-principles calculations, addressing previous uncertainties.

Findings

The lattice parameter correlates with magnetic moment and bond lengths.

The formula accurately predicts lattice parameters for various alloys.

It explains previously puzzling experimental anomalies.

Abstract

The addition of transition metals (TM) to III-V semiconductors radically changes their electronic, magnetic and structural properties. In contrast to the conventional semiconductor alloys, the lattice parameter in magnetic semiconductor alloys, including the ones with diluted concentration (the diluted magnetic semiconductors - DMS), cannot be determined uniquely from the composition. By using first-principles calculations, we find a direct correlation between the magnetic moment and the anion-TM bond lengths. We derive a simple formula that determines the lattice parameter of a particular magnetic semiconductor by considering both the composition and magnetic moment. The formula makes accurate predictions of the lattice parameter behavior of AlMnN, AlCrN, GaMnN, GaCrN, GaCrAs and GaMnAs alloys. This new dependence can explain some of the hitherto puzzling experimentally observed anomalies, as well as, stimulate other kind of theoretical and experimental investigations.